The aim of the study is to demonstrate the non-inferiority in terms of acute bronchodilator effect between a single dose of CHF 1535 NEXThaler 200/6 µg and a single dose of CHF 1535 NEXThaler 100/6 µg at two dose levels in partially controlled and uncontrolled asthmatic patients.

Inclusion Criteria:

• Patient's written informed consent obtained prior to any study-related procedures.
• Male or female aged between 18 and 65 years inclusive;
• Evidence for "partially controlled" or "uncontrolled" asthma;
• Medium daily dose of previous inhaled corticosteroids (ICS) treatment;
• FEV1 between 60% and 85% of the predicted normal values;
• A documented positive response to the reversibility test;
• Non-smokers or ex-smokers;
• A cooperative attitude and ability to be trained in the proper use of a DPI.

Exclusion Criteria:

• Pregnant or lactating women and all women physiologically capable of becoming pregnant not willing to use at least one acceptable method of contraception.
• Significant seasonal variation in asthma occurring or expected to occur during study participation;
• History of near fatal asthma, brittle asthma, accident and Emergency treatment or hospitalisation for asthma exacerbation in Intensive Care Unit within 1 year before screening;
• Occurrence of asthma exacerbations or respiratory tract infections in the 4 weeks preceding the screening;
• Diagnosis of Chronic Obstructive Pulmonary Disease;
• History of cystic fibrosis, bronchiectasis or alpha-1 antitrypsin deficiency;
• Diagnosis of restrictive lung disease;
• Patients treated with oral or parenteral corticosteroids in the previous 8 weeks;
• Intolerance or contra-indication to treatment with beta2-agonists and/or inhaled corticosteroids;
• Allergy, sensitivity or intolerance to study drugs or excipients;
• Patients who received any investigational drug within the last 8 weeks before the screening;
• Patients taking any of the non-permitted concomitant medication;
• Subjects unlikely to comply with the study protocol;
• Any clinically relevant abnormal value or physical finding at screening;
• Significant medical history;
• Abnormal and clinically significant 12-lead electrocardiogram;
• Patients with low compliance of QVAR intake.